If you are using it for bass, it pretty much HAS to have a 15"...
True. Which is why I still hang on to the Motion Sound powered sub. For small gigs including a bass player, all I need is the K1800FX. But on occasions were I am responsible for holding down the bass I can bring the sub and use the K1800FX's sub output.
I'm tellin'ya guys, Behringer stuff is just fine. I really think that most of those people who talk bad about the brand are just repeating what they heard and have no first hand experience. That is not to say that no one has ever had a problem with a piece of Behringer equipment. But no brand exists that can tout a 0% failure rate.